Little is known about the impact of macroeconomic conditions during pregnancy on fetal health, despite substantial evidence that the in utero environment is linked to later-life health. Previous studies have examined associations between economic conditions and birth outcomes, but critical gaps remain in our understanding of the causal relationship between these factors. For example, prior work has failed to distinguish the health effects of economic conditions during pregnancy from the selection effects of economic conditions on who is born. Existing work also has not thoroughly examined differences in the magnitude or direction of effects by maternal sociodemographic characteristics and race/ethnicity. In light of the recent Great Recession-the most devastating economic crisis since the 1930s-it is critical that we re-examine the relationship between macroeconomic conditions and fetal health, addressing limitations of previous work, and our interdisciplinary team (with expertise in epidemiology, economics, and biostatistics) is ideally positioned to do so. Our long-term goal is to determine whether macroeconomic conditions in utero have adverse impacts on fetal health and, if so, to understand the mechanisms behind these associations. The objective of this R03 application is to assess the effect of economic conditions during pregnancy on measures of fetal health in the context of the Great Recession. Using data from the comprehensive U.S. vital statistics natality files 2007-2011 and the Michigan maternal linked birth files linked to economic data from the Bureau of Labor Statistics, we will address 2 specific aims: 1) Examine the effects of state- and county-level macroeconomic conditions during pregnancy on birth outcomes, accounting for selection effects, and 2) Investigate whether the health effects of macroeconomic conditions during pregnancy on birth outcomes differ by maternal race/ethnicity, age, marital status, parity, or education. A key innovation of te proposed research is that it will bring together the disparate bodies of research on the etiology of adverse birth outcomes and the health effects of macroeconomic change. The proposed research is significant because it will provide the first evidence as to the impact of macroeconomic conditions in utero on birth outcomes in the context of the Great Recession. Moreover, examination of heterogeneity by race/ethnicity and sociodemographics will enable us to identify vulnerable subgroups and may shed light on mechanisms by which economic conditions impact fetal health.